In the past 20 years, the class of MEM models has grown in size, at times applying and extending concepts that were originated in the GARCH literature, also as a consequence of the fact that a GARCH model is a MEM for squared returns. Within the \(\mathsf {ACD}\) , from the already mentioned seminal contribution of [1]}, further developments for the financial durations are documented in [2]}; [3]} provide a local adaptive approach to \(\mathsf {ACD}\) 's, using \(\mathsf {MEM}\)  and \(\mathsf {ACD}\)  as synonyms; [4]} provide a testing framework for \(\mathsf {ACD}\)  parametric specifications. A \(\mathsf {MEM}\)  for the daily range [5]}, [6]} is called Conditional Autoregressive Range (CARR) model by [7]} and a review of this approach is contained in [8]}.
